Encrypt messages with Advanced Email Security
Microsoft 365 automatically encrypts all messages sent within your organization. To protect any sensitive information when sending to external recipients, like customers or vendors, you need to manually encrypt your email. With Advanced Email Security, an encryption filter is already built in — which means all you need to do is edit your message's subject line to encrypt it.
Send an encrypted message
To encrypt an email, add [Encrypt] at the beginning of the subject line. This works on any email client and any device.
After sending the message, you'll receive an email confirming the message was encrypted.
The recipient will receive an email with instructions on how to sign in to Advanced Email Security to view and respond to the encrypted message. The email expires after 15 days and the recipient cannot forward or save it (but they can download attachments from the email).
View an encrypted message that was sent to you
When you receive an encrypted message, you’ll receive an email notification (you'll see the subject line "You have received an encrypted email"). To view the message, select View Encrypted Email, and then sign in to the encryption portal. You'll need to register and verify your email address if you don't have an account.
You'll see a list of sent and received messages, sorted by date, on the leftmost side when you're signed in. Select a message to decrypt it and view it. To send a response, select Reply.
Limitations for encrypted messages
Keep the following limitations in mind when sending and receiving encrypted messages with Advanced Email Security from Proofpoint:
- Encrypted outbound messages must be less than 35 MB, including attachments.
- Encrypted outbound messages can only have up to 256 files attached.
- By default, Advanced Email Security keeps encrypted messages for 15 days.
Microsoft 365 limitations also still apply.
- What is Advanced Email Security?
- Learn more about linked domains and organizations in Microsoft 365.
- What do the banners from Advanced Email Security mean?
- If these steps don't match your Advanced Email Security dashboard, you might be on INKY. Check out our PDF for help with Advanced Email Security powered by INKY.